Epoxide modified polysulfide polymers as adhesive additives for liquid polysulfide polymer based adhesive compositions

ABSTRACT

Polysulfide polymers modified with epoxy groups are effective as adhesive additives for liquid polysulfide polymer based compositions used as sealants or bonding agents on various substrates such as glass or aluminum.

This is a continuation of application Ser. No. 377,161 filed July 6,1973 now abandoned which is a division of Ser. No. 252,646 filed May 12,1972, now U.S. Pat. No. 3,813,368.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to improved liquid polysulfide polymer basedadhesive compositions containing novel adhesive additives. Moreparticularly, this invention relates to improved liquid polysulfidepolymer based adhesive compositions containing novel adhesive additivesprepared by modifying polysulfide and polyester polymers with abieticacid and polysulfide polymers with epoxy groups.

2. Description of the Prior Art

Curable, liquid polysulfide polymer based sealant and caulkingcompositions have long been known in the art. They are based on curable,liquid, mercaptan terminated polysulfide polymers. The structure andpreparation of these polythiopolymercaptan polymers are disclosed inU.S. Pat. No. 2,466,963. These liquid, mercaptan terminated polymers areused extensively in sealant and caulking compositions, especially in thebuilding, automotive, and marine industries; for castings, e.g., solidrocket propellants; for leather and textile impregnating agents; foradhesives, coatings, etc. Because of the wide range of applications inwhich these polysulfide polymer based sealing and caulking compositionsare used, they must be capable of bonding to various substrates, e.g.,metal, aluminum, glass, concrete, wood, etc. However, the adhesivequalities of polysulfide polymers are such as to usually require the useof an adhesive additive in the polysulfide polymer based sealantcomposition in order to insure adequate bonding of the cured sealant tothe substrate.

Adhesive additives of the prior art such as those of a phenolic natureprovided only a polar, rather than a chemical, type bonding of the curedsealant to the substrate. Thus, sealant compositions containing phenolictype adhesive additives were found to be susceptible to attack by polarsolvents such as water. The polar solvent tended to break down the polarbond thereby impairing the utility of the sealant composition. Morerecently, as disclosed in U.S. Pat. Nos. 3,297,473; 3,312,669, and3,328,451, certain organo-silanes e.g., (mercapto alkyl amino alkylalkoxyl silanes) have been proposed to overcome these problems. However,while the organo-silane adhesive additives have been found to protectthe sealant composition bonds from attack by polar solvents, they dohave certain disadvantages. Thus, the organo-silane adhesive additivesare economically costly, somewhat deficient in storage stability, andexhibit erratic adhesion results with certain substrates, such asconcrete.

The object of the present invention, therefore, is to provide a novelliquid polysulfide polymer based caulking or sealant composition whichwill allow for the attainment of a strong and lasting bonding of thesealant to the substrates to be treated therewith.

Another object of the present invention is to provide a novel liquidpolysulfide polymer based caulking or sealant composition containingadhesive additives which are less costly, exhibit improved storagestability, and which exhibit more reproducible and uniform adhesioncharacteristics to a wider range of substrates.

Other objects of the invention will become apparent to those skilled inthe art from a consideration of the following detailed description.

SUMMARY OF THE INVENTION

It has now been unexpectedly found that the objects set forth above canbe accomplished by the use of an abietate terminated polysulfidepolymer, an abietate terminated polyester polymer, or an epoxyterminated polysulfide polymer as an adhesive additive for the liquidpolysulfide polymer based sealant composition.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As indicated previously, the novel adhesive additives of the presentinvention are the abietate terminated polysulfide polymers, the abietateterminated polyester polymers, and the epoxy terminated polysulfidepolymers. Of these adhesive additives, the abietate terminatedpolysulfide polymers are preferred because they exhibit more uniform andreproducible adhesion results to various substrates when incorporatedinto a liquid polysulfide polymer based sealant composition. Theabietate terminated polyester polymer and epoxy terminated polysulfidepolymer adhesive additives show increased adhesion to certainsubstrates. However, it has been found that larger quantities of theselatter adhesive additives are required to produce increased adhesionresults. The use of these adhesive additives in the required quantitiesoften results in some retardation of the cure rate of the sealantcomposition. Moreover, adhesion results on the abietate terminatedpolyester polymer and epoxy terminated polysulfide polymer adhesiveadditives have not proven to be as uniform nor as reproducible as thepreferred abietate terminated polysulfide polymer adhesive additive. Forthat reason, it is recommended that the abietate terminated polyesterpolymer and epoxy terminated polysulfide polymer adhesive additives beused at not more than 5 parts by weight of additive per 100 parts byweight of liquid polysulfide polymer based on the total weight of thesealing composition. Larger quantities of these adhesive additives mayrequire an adjustment in the amount of curing agents employed.

The abietate terminated polysulfide polymer adhesive additive of thepresent invention may be prepared by reacting a relatively low molecularweight, e.g., 500 to 4000, preferably 500 to 1500, SH terminated liquidpolysulfide polymer (hereinafter referred to as a liquid polythiolpolymer) with abietic acid at temperatures of from 150° C to 200° C. Thereaction is preferably carried out in a solvent medium and under aninert atmosphere.

The liquid polythiol polymer used as the starting material for reactionwith the abietic acid may include those polythiopolymercaptan polymersas are disclosed in U.S. Pat. No. 2,466,963 and which may be representedby the formula HS-(RSS)_(n) -RSH where R is a hydrocarbon,oxahydrocarbon or thiahydrocarbon radical such as the ethyl formalradical

    (--CH.sub.2 --CH.sub.2 --O--CH.sub.2 --O--CH.sub.2 --CH.sub.2 --)

the butyl formal radical

    (--CH.sub.2 --CH.sub.2 --CH.sub.2 --CH.sub.2 --O--CH.sub.2 --O--CH.sub.2 --CH.sub.2 --CH.sub.2 --CH.sub.2 --)

the ethyl radical

    (--CH.sub.2 --CH.sub.2 --O--CH.sub.2 --CH.sub.2 --)

and the butyl ether radical

    (--CH.sub.2 --CH.sub.2 --CH.sub.2 --CH.sub.2 --O--CH.sub.2 --CH.sub.2 --CH.sub.2 --CH.sub.2 --)

and n will vary from about 4 to 23.

A preferred liquid polythiol polymer will have a molecular weight of 500to 4000. A particularly preferred liquid polythiol polymer used in thepractice of the present invention is a liquid polythiol polymercontaining no crosslinking and having a molecular weight of 1000.

While the reaction between the liquid polythiol polymer and abietic acidis not known with exact certitude, it is theorized that the reactionproceeds with inversion of a mercaptan terminal to a hydroxyl terminalfollowed by esterification. The reaction is believed to proceed in thefollowing manner:

1. HS--(C₂ H₄ --O--CH₂ --O--C₂ H₄ --SS)_(n) --C₂ H₄ --O--C₂ H₄ SH^(heat) HS--(C₂ H₄ --O--CH₂ --O--C₂ H₄ --SS)_(n) --C₂ H₄ --O--CH₂--S--C₂ H₄ --OH ##STR1## wherein n will vary from 4 to 23.

As indicated previously, the reaction product of the liquid polythiolpolymer and abietic acid is believed to be predominantly of the generaltype structure shown above. However, it should be observed here that thereaction product may in fact contain a mixture of chemical structures.Thus, it is likely that in addition to the above structure, the reactionproduct may contain structures wherein there are abietate terminals atboth ends of the polysulfide polymer chain and in addition may containunreacted liquid polythiol polymer with SH terminals at both ends of thepolymer chain. The predominant type structure obtained is influenced inlarge measure by the reaction conditions employed. The abietateterminated polysulfide polymer adhesive additive may be incorporatedinto the liquid polysulfide polymer based sealant composition in amountsof from 0.5 to 3.5 parts by weight per 100 parts by weight of liquidpolysulfide polymer.

The abietate terminated polyester polymer adhesive additive may beprepared by any of several procedures. For example, a hydroxylterminated liquid polyester polymer of relatively low molecular weighte.g. 500 to 2500, preferably 500 to 1500, may be reacted with abieticacid under an inert atmosphere at temperatures ranging from about 140°to 200° C. with or without the presence of a solvent. Alternatively, theindividual components which react to form the hydroxyl-terminated liquidpolyester polymer may be directly admixed with the abietic acid in asuitable mixing apparatus and then reacted to form the abietateterminated polyester polymer used as the adhesive additive in thecompositions of the present invention.

The hydroxyl-terminated liquid polyester polymers which may be reactedwith abietic acid to form the abietic terminated polyester polymeradhesive additives of the present invention may be virtually any ofthose known to the art. These hydroxyl-terminated liquid polyesterpolymers may be prepared in known manner by reacting diols or polyolswith dicarboxylic or polycarboxylic acids under temperature and pressureconditions known in the art. Typical dicarboxylic acids useful inpreparing the polyesters include oxalic, adipic, azelaic, sebacic,maleic, and fumaric acids and others, as well as mixtures of theseacids. The diols used may include ethylene glycol, diethylene glycols,alkane diols, caster oil and the like. As indicated previously, theliquid polyesters preferably have a molecular weight of 500 to 2500.

Liquid polyester polymers containing sulfur in the polyester moleculeare particularly preferred in the practice of the present inventionsince they are believed to be more compatible with the liquidpolysulfide polymer of the sealant composition. A preferred abietatemodified sulfur containing polyester polymer adhesive additive of thepresent invention may be prepared by mixing and reacting thiodiethyleneglycol, azelaic acid, maleic anhydride, and abietic acid under an inertatmosphere at a temperature of 130° to 190° C. The resulting abietateterminated polyester polymer adhesive additive may be incorporated intothe liquid polysulfide polymer based sealant composition in amountsranging from 0.5 to 5.0 parts by weight per 100 parts of liquidpolysulfide polymer. At the higher concentration some retardation of thesealant composition cure rate is observed.

The epoxy modified polysulfide polymers used as adhesive additives inthe compositions of the present invention may be prepared by reacting arelatively low molecular weight e.g. 500 to 1500, liquid polythiolpolymer, such as the liquid polythiol polymer described previously, witha diepoxide such as vinyl cyclohexane diepoxide in a solvent medium inthe presence of an acid catalyst. The chemical reaction between theliquid polythiol polymer and vinyl cyclohexane diepoxide is theorized toproceed as follows: ##STR2## where R is the ethyl formal radical

    (--CH.sub.2 --CH.sub.2 --O--CH.sub.2 --O--CH.sub.2 --CH.sub.2 --)

and n may vary from 4 to 23.

In the above reaction, the epoxy cyclohexane group is reactive underacidic conditions whereas the epoxy ethyl group is reactive under basicconditions. The chemical structure shown above is believed to be thepredominant form of the reaction product. However, it should be observedthat the reaction product very possibly may consist of a mixture ofmaterials with varying structures. Thus, it is possible that thereaction product in addition to the above structure may contain aproduct wherein the polysulfide polymer has an epoxy terminal at bothends of the polymer chain or a portion of the reaction product has SHterminals at both ends of the polymer chain.

A particularly preferred epoxy terminated polysulfide polymer adhesiveadditive of the present invention is prepared by reacting a liquidpolythiol polymer of 1000 molecular weight having no crosslinking withvinyl cyclohexane diepoxide in a solvent medium in the presence of anacid catalyst.

The reaction product of a liquid polythiol polymer and a diepoxide is anepoxy terminated polysulfide resin which can be incorporated into theliquid polysulfide polymer based sealant composition in an amountranging from 0.5 to 5.0 parts by weight of epoxy terminated polysulfideresin per 100 parts by weight of polysulfide polymer. At the higherconcentration of adhesive additive, some retardation of sealantcomposition cure rate is observed.

The liquid polysulfide polymers which form the polymer base of thesealant or caulking compositions with which the novel compounds of thepresent invention are used as adhesive additives are those liquidpolythiopolymercaptan polymers as are disclosed and claimed, as notedabove, in U.S. Pat. No. 2,466,963. The most preferred of such polymersfor the purposes of making sealant or caulking compositions are thosehaving a molecular weight of about 500 to 4000.

The liquid polysulfide polymer curing agents which may be used insealant compositions with the novel adhesive additive compounds of thepresent invention include all those materials known to the art as liquidpolysulfide polymer curing agents such as polyepoxy resins, leadperoxide, calcium peroxide, zinc peroxide, lithium peroxide, bariumperoxide, tellurium dioxide and the various chromate salts as aredisclosed in U.S. Pat. No. 2,964,503. In addition, as disclosed in U.S.Pat. No. 3,487,052 various other inorganic oxides and peroxides, organicperoxides, permanganates, organo tin compounds, organic nitro compounds,and quinoid compounds can often be advantageously used as curing agentsfor said liquid polysulfide polymers. About 2 to 10 parts by weight ofone or more of such curing agents should be used in such compositionsper 100 parts by weight of liquid polysulfide polymer being used.

Curable liquid polysulfide polymer based sealant compositions used inconjunction with the adhesive additive compounds of the presentinvention may also contain various types of inert materials commonlyemployed in liquid polysulfide polymer based sealant compositions suchas fillers, plasticizers, pigments, ultraviolet light stabilizers, cureaccelerators, and the like.

The substrates which can be treated with sealant compositions containingthe novel adhesive additives of the present invention include those of awood nature, those of a silicaceous nature such as glass, those of ametallic nature such as aluminum, iron, and steel, and to a limiteddegree concrete.

In order to illustrate further the nature of the present invention, thefollowing examples are submitted. These examples are merely illustrativeof the present invention and are not intended as a limitation upon thescope thereof.

EXAMPLE 1 Preparation of Abietate Terminated Liquid Polysulfide PolymerResin

A 4000 ml. resin kettle equipped with a Barret trap, a thermometer andadapter, an electric stirrer, a gas inlet tube and a Fredricks condenserwas charged with 2000 grams (2 moles) of a liquid polythiol polymer of1000 mol. weight having no crosslinking, 604.88 grams (2 moles) ofabietic acid, and 150 mls. of xylene. The mixture was heated under anitrogen atmosphere for approximately 1 hour 15 minutes at which timethe temperature had reached 190° C. and 10 mls. of H₂ O had collected inthe Barret trap. The mixture was then heated for approximately 21/2hours at 190° C. at which time 34 mls. of H₂ O had collected in thetrap. The mixture was heated for an additional 10 minutes and the heatthen removed. A sample of resinous product was removed from the resinkettle and analyzed for SH percentage. SH percent was found to be 2.7%.The next morning, heat was again applied to the mixture forapproximately 2 hours at 165° C. An additional 61/2 mls. of H₂ Ocollected in the trap for a total of 41 mls. of H₂ O collected andremoved during the reaction. Heat was removed at this time and a sampleof resinous product analyzed for SH percentage. Analysis indicated thatSH percentage was 0.5%. A vacuum was hooked up to the reaction apparatusand the reaction was heated to 70° C. until all of the xylene had beenevaporated. The resinous abietate terminated polysulfide polymer wascollected and the acid number and hydroxyl number determined. Resultswere as follows:

    ______________________________________                                                  Acid No.    OH No.                                                  ______________________________________                                        1.          29.85         129.89                                              2.          29.14         129.49                                              ______________________________________                                    

About 5.5 pounds of abietate terminated polysulfide polymer resin wasprepared by the above procedure and used as an adhesive addition in theexamples which follow.

EXAMPLES 2-4 Evaluation of The Abietate Terminated Polysulfide PolymerResin of Example 1 as an Adhesive Additive in Liquid Polysulfide PolymerBased Sealant Compositions

In order to determine the effectiveness of the abietate terminatedpolysulfide polymer resin of Example 1 as an adhesive additive, a liquidpolysulfide polymer based sealant masterbatch of the followingformulation was prepared using mixing procedures well known in thesealant art:

    ______________________________________                                        Ingredients           Parts by Weight                                         ______________________________________                                        LP-32 Polysulfide Polymer                                                                           100.0                                                   Multiflex MM (Calcium Carbonate)                                                                    25.0                                                    Icecap R (Anhydrous Clay)                                                                           30.0                                                    Titanox RA 50 (Titanium Dioxide)                                                                    10.0                                                    Arochlor 1254 (Chlorinated Diphenyl)                                                                35.0                                                                          200.0                                                   ______________________________________                                         *LP-32 polysulfide polymer has essentially the structure HS--(--C.sub.2       H.sub.4 --O--CH.sub.2 --O--C.sub.2 H.sub.4 --SS).sub.23 --C.sub.2 H.sub.4     --O--CH.sub.2 --O--C.sub.2 H.sub.4 --SH with about 0.5% crosslinking and      molecular weight of about 4000.                                          

A control formulation (Example 2) for this evaluation was prepared bycombining the above sealant masterbatch with a lead peroxide curingpaste (described hereinafter). One test formulation (Example 3) wasprepared by combining the sealant masterbatch with the abietateterminated polysulfide polymer resin and a lead peroxide curing paste.An additional test formulation (Example 4) was prepared by combining thesealant masterbatch with the abietate terminated polysulfide polymerresin and a zinc peroxide curing paste (described hereinafter). Thecontrol and test formulations were as follows:

    __________________________________________________________________________                               Parts by Weight                                    Formulation          Ex. No.                                                                             2    3    4                                        __________________________________________________________________________    Polysulfide Sealant Masterbatch                                                                          200.0                                                                              200.0                                                                              200.0                                    Abietate Terminated Polysulfide Polymer                                       Adhesive Additive          --    1.0  1.0                                     Lead Peroxide Curing Paste  15.0                                                                               15.0                                                                              --                                       Zinc Peroxide Curing Paste --   --    22.0                                    __________________________________________________________________________

The lead peroxide curing paste shown above is a mixture of lead peroxideand arochlor 1254 containing 50% PbO₂. Arochlor 1254 is a chlorinateddiphenyl plasticizer. The zinc peroxide curing paste shown above is amixture of zinc peroxide, arochlor 1254, and amax containing 45.5% ZnO₂,45.5% arochlor 1254, and 9% amax. Amax is n-oxy-diethylenebenzothiozole-2-sulfamide and is used as a cure accelerator.

Peel adhesion strength specimens bonded to glass and aluminum substrateswere prepared from the above formulations. These specimens were exposedto 7 days in air at room temperature, 7 days in an oven at 158° F., and7 days immersion in room temperature water. Peel adhesion values wereobtained upon removal of the specimens from water immersion while thesamples were still wet using an Instron tester. The results of the peeladhesion tests are shown in Table I.

                  TABLE I                                                         ______________________________________                                        Adhesion Peel Strength Valves (PSI)                                                   Substrate                                                                     Glass        Aluminium                                                Example   Test 1    Test 2   Test 1  Test 2                                   ______________________________________                                        2 (Control)                                                                              NA*      NA       NA      NA                                       3         52        53       28      28                                       4         46        53       30      31                                       ______________________________________                                         *NA = No adhesion                                                        

The control specimens showed complete adhesion failure to both the glassand aluminium substrates.

EXAMPLE 5 Evaluation of The Abietate Terminated Polysulfide PolymerResin As An Adhesive Additive in a Liquid Polysulfide Polymer BasedSealant Composition Utilizing a Calcium Peroxide Curing System

In this example, the abietate terminated polysulfide polymer resin wascombined with the polysulfide sealant masterbatch shown below, curedwith a calcium peroxide curing paste (described below) and then testedfor peel adhesion using the procedure described in Examples 2-4.

    ______________________________________                                        Polysulfide Sealant Masterbatch                                                                       Parts by Weight                                       ______________________________________                                        LP-32 polysulfide polymer                                                                             100.0                                                 Witcarb RC (precipitated calcium carbonate)                                                           40.0                                                  Cameltex (calcium carbonate)                                                                          25.0                                                  Titanox RA 50 (titanium dioxide)                                                                      10.0                                                  Thixcin GR (thixotropic agent)                                                                        10.0                                                  Aroclor 1254 (chlorinated diphenyl)                                                                   20.0                                                  Santicizer 160 (butyl benzylphtalate)                                                                 20.0                                                                          225.0                                                 ______________________________________                                    

As indicated previously, the above sealant masterbatch was combined withthe abietate terminated polysulfide polymer resin and a calcium peroxidecuring paste to form the test formulation. The test formulation is shownbelow.

    ______________________________________                                        Polysulfide Sealant Test Formulation                                          Ingredients             Parts by Weight                                       ______________________________________                                        Polysulfide Sealant Masterbatch                                                                       225.0                                                 Abietate Terminated Polysulfide Polymer Resin                                                         1.0                                                   Calcium Peroxide Curing Paste                                                                         37.5                                                  ______________________________________                                    

The above calcium peroxide curing paste is a mixture of CaO₂, Titanox RA50, Calcium Hydroxide, and Arochlor 1254 containing 26.7% CaO₂, 13.3%Titanox RA 50, 6.6% Calcium Hydroxide, and 53.4% Arochlor 1254.

As indicated previously, the above formulation was tested for peeladhesion strength using the procedure described in Examples 2-4. Testresults are shown in Table II.

                  TABLE II                                                        ______________________________________                                        Adhesion Peel Strength Valves (PSI)                                                   Substrate                                                                     Glass        Aluminium                                                Example   Test 1    Test 2   Test 1  Test 2                                   ______________________________________                                        5         46        53       30      31                                       ______________________________________                                    

EXAMPLES 6-7 Evaluation of The Effect of The Abietate TerminatedPolysulfide Polymer Resin on the Storage Stability of a Two PackagePolysulfide Polymer Based Sealant Composition

In these examples, the effect of the abietate terminated polysulfidepolymer resin on the storage stability of a two package sealantcomposition was determined by admixing said resin with the polysulfidesealant masterbatch used in examples 2-4 and then aging the admixture inan oven for 7 days at 158° F. A sample of the above oven aged admixturewas then combined with lead peroxide curing paste to form one testformulation (Example 6) while an additional sample of the oven agedadmixture was combined with zinc peroxide curing paste to form a secondtest formulation (Example 7). Specimens of the test formulations bondedto aluminum and glass substrates were then prepared for peel adhesionstrength tests in accordance with the procedure described in Examples2-4. The test specimens were then aged for 7 days in air at roomtemperature, 7 days in an oven at 158° F., and 7 days immersed in roomtemperature water.

In essence, this evaluation serves to measure the effect of hightemperature storage on a two package sealant composition wherein theabietate terminated polysulfide polymer resin is incorporated into theliquid polysulfide polymer based sealant package. Thus, the test is alsoa measure of the storage stability of the resin as an adhesive additive.

The test formulations and peel adhesion values as determined on aInstron tester are shown in Table III.

                  TABLE III                                                       ______________________________________                                                             Parts by Weight                                          Test Formulations Ex. No.  6        7                                         ______________________________________                                        Polysulfide sealant masterbatch                                                                      200.0    200.0                                         Abietate terminated polysulfide                                               polymer resin           1.0      1.0                                          Lead peroxide curing paste                                                                            15.0    --                                            Zinc peroxide curing paste                                                                           --        22.0                                         ______________________________________                                        Adhesion Peel Strength (PSI)                                                          Substrate                                                                     Glass        Aluminium                                                Example   Test 1    Test 2   Test 1  Test 2                                   ______________________________________                                        6         75        77       29      38                                       7         41        38       30      28                                       ______________________________________                                    

The above peel strength data indicates that the abietate terminatedpolysulfide polymer resin did not adversely affect peel strengthadhesion values of the polysulfide sealant composition even when exposedto high temperature aging storage conditions. In fact, when compared tothe peel adhesion values of Table I wherein the same compositions weretested without prior oven aging of the sealant masterbatch, theseadhesion results are equal to or better than the results shown therein.Thus, the abietate terminated polysulfide polymer resin exhibitsexcellent storage stability.

EXAMPLE 8 Preparation of Abietate Terminated Polyester Resin AdhesiveAdditive

A 1000 ml. resin pot equipped with a Barret trap, a thermometer andadapter, an electric stirrer, a gas inlet tube, and a FredricksCondenser is charged with 299.20 grams (2.45 moles) of thiodiethyleneglycol, 165.35 grams (0.88 moles) of azelaic acid, 86.02 grams (0.88moles) of maleic anhydride, and 170.00 grams (0.56 moles) of abieticacid. The mixture was heated under a helium atmosphere for about 11/2hours at temperatures of 130° to 150° C., at which time 29 mls. of H₂ Ohad collected in the trap. The mixture was permitted to stand overnight.The next morning heat was again applied to the reaction mixture and itwas heated for 2 hours at which time the temperature was 190° C. and atotal of 55 mls. of H₂ O had collected in the trap. At this time,approximately 35 mls. of xylene were added to the reaction mixture. Themixture was then heated for an additional 6 hours at temperaturesranging from 185° to 200° C. at which time a total of approximately 64mls. of H₂ O had collected in the trap. At this point, the reactionmixture had been heated for a total of approximately 8 hours. Thereaction mixture was again permitted to stand overnight. The nextmorning heat was again applied to the reaction mixture and the mixtureheated for approximately 6 hours at temperatures of 150° to 175° C. atwhich time a total of about 66 mls. of H₂ O had collected in the trap.At this time, heat was removed and the reaction mixture allowed to coolto 100° C. A vacuum system was then hooked to the reaction mixtureapparatus and the reaction heated at 150° C. for 2 hours under 7 mm ofHg pressure to remove any H₂ O or solvent remaining in the resinousproduct. A sample of resin product was analyzed for OH No. and acid No.with the following results: OH No. = 13.11, acid number = 37.40, 38.72.A total of 645 grams of abietate terminated polyester resin wereproduced during the reaction.

EXAMPLES 9-12 Evaluation of Abietate Terminated Polyester Resin As AnAdhesive Additive In Polysulfide Sealant Formulations

In these examples, the abietate terminated polyester resin of Example 8was evaluated at 1% and 5% levels in the polysulfide sealant masterbatchof Examples 2-4 according to the following formulations:

    __________________________________________________________________________                              Parts by Weight                                     Formulation         Ex. No.                                                                             9     10    11    12                                __________________________________________________________________________    Polysulfide Sealant Masterbatch                                                                         200.0 200.0 200.0 200.0                             Abietate Terminated Polyester Resin                                                                     1.0   5.0   1.0   5.0                               Lead Peroxide Curing Paste                                                                              15.0  15.0  --    --                                Zinc Peroxide Curing Paste                                                                              --    --    22.0  22.0                              __________________________________________________________________________

to form the curable sealants 8, 9, 10, and 11. The above sealantcompositions were applied as beads in duplicate to clean unprimed glass,aluminum, and concrete panels and left to cure for 7 days in air at roomtemperature. One set of duplicates was tested for adhesion. The otherset of panels was then immersed in tap water for 7 days at roomtemperature and then tested for adhesion. The adhesion tests consistedof attempting to peel the cured sealant beads from the substrates. Ifthe bead could not be removed without tearing the bead, this was notedas a cohesive failure. If the bead peeled off it was noted as anadhesive failure. If the bead separated during water immersion or ifvirtually no force was required to remove the bead, it was noted ashaving no adhesion (NA). Results of these adhesion tests are shown inTable IV.

                                      TABLE IV                                    __________________________________________________________________________    Conditions            7 Days in Air at Room Temp.                                                                   7 Days in Water                         Substrate             Glass                                                                             Aluminum                                                                            Concrete                                                                            Glass                                                                             Aluminum                                                                            Concrete                      __________________________________________________________________________    Example No.                                                                           % Additive                                                                          Curing Agent                                                    __________________________________________________________________________    9       1     PbO.sub.2 paste                                                                       C   NA    NA    C   A     NA                            10*     5     PbO.sub.2 paste                                                                       C   NA    NA    NA  A     NA                            11      1     ZnO.sub.2 paste                                                                       C   NA    NA    NA  NA    NA                            12*     5     ZnO.sub.2 paste                                                                       C   C     NA    NA  NA    NA                            __________________________________________________________________________     *At the 5% level of adhesive additive, the sealant compositions were not      completely cured.                                                             Code:                                                                         C = Cohesive Failure                                                          A = Adhesive Failure                                                          NA = No adhesion                                                         

The data indicates that the sealant composition containing 1% adhesiveadditive and lead peroxide curing agent (Example 8) gave good adhesionto glass in both the air and water tests.

EXAMPLE 13 Preparation of Epoxy Terminated Polysulfide Resin AdhesiveAdditive

A 500 ml. B necked RB flask equipped with an air condenser, thermometer,stirring rod and mixer was charged with 100 mls. of Dioxane, 0.5 gramsp-toluene sulfonic acid, 200 grams of liquid polythiol polymercontaining no crosslinking and having a molecular weight of 1000, and 59grams of vinyl cyclohexane diepoxide. The reaction was designed toterminate when a 50% reduction of the estimated SH% and epoxy group % ofthe original reactants was obtained. The liquid polythiol polymercontained an estimated 6.4% SH and the vinyl cyclohexane reactantcontained an estimated 0.34% epoxy groups. The reaction mixture washeated to 50° C. for 6 hours and 55 minutes. At this time, the reactionmixture was heated to reflux at 113° C. for 7 hours and 40 minutes.During this period, the reaction mixture was sampled and analyzed forSH% and epoxy %. Analysis of these groups showed less than 50% reductionin SH% and epoxy %. Accordingly, the mixture was permitted to standovernight. On the next day, heat was again applied to the reactionmixture and it was heated for an additional 6 hours at 111° C. At thispoint, a sample of reaction product was analyzed and SH% was found toequal 3.39% and epoxy percent was found to equal 0.171%. This indicatedan approximate reduction of 50% in the original SH and epoxy grouppercentages. The reaction mixture was then placed in a rotor vacuumwater asperator and a hot water bath to evaporate the solvent. Theexperimental procedure yielded 211.2 grams of product. Total heatingtime of the reaction mixture was about 20 hours.

EXAMPLES 14-17 Evaluation of Epoxy Terminated Polysulfide Resin as anAdhesive Additive in a Polysulfide Sealant Composition

In these examples, the epoxy terminated polysulfide resin of Example 12was evaluated in the polysulfide sealant masterbatch of Example 2 at a1% and 5% level in the following formulations:

    __________________________________________________________________________                             Parts by Weight                                      Formulation        Ex. No.                                                                             14    15    16    17                                 __________________________________________________________________________    Polysulfide Sealant Masterbatch                                                                        200.0 200.0 200.0 200.0                              Epoxy Terminated Polysulfide Resin                                                                     1.0   5.0   1.0   5.0                                Lead Peroxide Curing Paste                                                                             15.0  15.0  --    --                                 Zinc Peroxide Curing Paste                                                                             --    --    22.0  22.0                               __________________________________________________________________________

Adhesions of the above curable formulations were run in accordance withthe procedure described in Examples 8-11. Adhesion results are shown inTable V.

                                      TABLE V                                     __________________________________________________________________________    Conditions            7 Days in Air at Room Temp.                                                                   7 Days in Water                         Substrate             Glass                                                                             Aluminum                                                                            Concrete                                                                            Glass                                                                             Aluminum                                                                            Concrete                      __________________________________________________________________________    Example No.                                                                           % Additive                                                                          Curing Agent                                                    __________________________________________________________________________    14        1   PbO.sub.2 paste                                                                       A   NA    C     NA  NA    NA                            15        5*  PbO.sub.2 paste                                                                       C   C     C     C   C     NA                            16        1   ZnO.sub.2 paste                                                                       C   NA    C     NA  NA    NA                            17        5*  ZnO.sub.2 paste                                                                       C   C     C     C   C     NA                            __________________________________________________________________________     *Some minor cure retardation noted at 5% level of additive in both            ZnO.sub.2 and PbO.sub.2 cured stocks                                          Code:                                                                         C = Cohesive Failure                                                          A = Adhesive Failure                                                          NA = No Adhesion                                                         

The above data shows that the epoxy terminated polysulfide adhesiveadditive at the 5% level gave excellent adhesion to glass and aluminumsubstrates in both the ZnO₂ and PbO₂ cured sealants and in both air andwater adhesion tests.

Now having fully described my invention, I claim:
 1. A curable liquidpolysulfide polymer based sealant composition containing, as an adhesiveadditive, 0.5 to 5.0 parts by weight of epoxy terminated polysulfideresin per 100 parts by weight of curable liquid polysulfide polymer. 2.The sealant composition of claim 1 wherein the epoxy terminatedpolysulfide resin is epoxy terminated substantially at one end of thepolymer chain.
 3. The sealant composition of claim 2 wherein the epoxyterminated polysulfide resin is the reaction product prepared byreacting a liquid polythiol polymer having a molecular weight of 500 to4000 and vinyl cyclohexane diepoxide until about a 50% reduction in thepercent thiol and epoxy functions in the reaction mixture has beenobtained.
 4. The sealant composition of claim 2 containing about 2.0 toabout 10.0 parts by weight of liquid polysulfide polymer curing agent.5. The sealant composition of claim 3 containinga. 100 parts by weightof curable liquid polysulfide polymer base, b. about 0.5 to about 5.0parts by weight of epoxy terminated polysulfide resin, and c. about 2.0to about 10.0 parts by weight of liquid polysulfide polymer curingagent.
 6. The sealant composition of claim 5 wherein the epoxyterminated polysulfide resin is derived from a liquid polythiol polymerwhich is non-cross linked and has a molecular weight of 1000.